High pressure fuel reservoir

ABSTRACT

A high-pressure fuel reservoir for a fuel injection system for internal combustion engines, which is supplied with high-pressure fuel by a high-pressure fuel pump and which has connections embodied as connection stubs, from each of the connection stubs one connecting bore discharges into the tubular body eccentrically to the axis of the tubular body. The tubular body is produced by forging, with three connecting stubs and fastening elements formed on by forging.

PRIOR ART

The invention is based on a high-pressure fuel reservoir for a vehicle.One such high-pressure fuel reservoir, known from European PatentDisclosure EP 0 507 191, comprises a prefabricated tube onto whichconnection cuffs are slipped to connect the fuel injection valves, orthe high-pressure line arriving from the high-pressure fuel pump. Such ahigh-pressure fuel reservoir is relatively expensive to produce andmoreover, because of the connection parts that have to mounted on it,requires a relatively large amount of installation space. In addition,it must have very thick walls in order to withstand the high pressuresunder the cyclic loads to which it is exposed. One disadvantage here isthat thick-walled bodies subjected to major cyclic pressure loads tendto rip apart, especially in the area of openings in the walls and wherethere are sharp-edged changes in cross section.

ADVANTAGES OF THE INVENTION

By means of the high-pressure fuel reservoir of the invention, ahigh-pressure fuel reservoir is obtained that because of the eccentriclocation of the connecting bores is especially capable of withstandingthe cyclic loads. Because of this eccentric location, the individualloads, in the region of a intersection with the inner wall of thehigh-pressure reservoir, are superimposed on one another onlyvectorially, resulting in an approximately 30% reduction in the loads.This substantially increases the strength and thus prolongs the servicelife of the high-pressure reservoir.

An advantageous feature is that the connecting bores discharge at atangent to the inner wall of the tubular body. This further reinforcesthe aforementioned effect. To avoid abrupt cross-sectional transitionsand thus to further reduce the partial heavy load on wall crosssections, an embodiment set forth herein is especially advantageous, inwhich the tubular body is shaped by forging, with connection stubslikewise formed by forging. This has the further advantage of requiringless installation shape, since the connections, because they areintegral with the tubular body, can be made substantially smaller. Inaddition, the high-pressure reservoir is thus lower in weight.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a high pressure fuel reservoir; and

FIG. 2 is a cross-sectional view along lines II—II of FIG. 1.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

In FIG. 1 of the drawing, a high-pressure fuel reservoir is shown, whichcomprises an elongated, forged tubular body 1, which on its jacket facehas connecting stubs 2, formed by forging, for supplying four fuelinjection valves, and which has fastening elements 3 formed onto thejacket face diametrically opposite the connecting stubs 2. The fasteningelements take the form of fastening eyelets or tabs, with through holes4 to be made by drilling, as can be seen from the section II—II in FIG.2. On its face ends 5, an axial through recess 10 (FIG. 2) forming theinterior of the high-pressure reservoir and embodied here as a throughbore is firmly closed. An inlet from a high-pressure fuel pump, notshown here, to the interior of the high-pressure reservoir is formed byan additional connecting stub 6 located between two fuel injectionvalves connections. On the side of the fastening elements 3, the tubularhigh-pressure reservoir can have still another connecting stub 7, intowhich a pressure sensor or a control valve, for instance, can bescrewed. The connecting stubs 2 are provided with a screw thread 8 inthe usual way, into which high-pressure connecting lines can be insertedtightly, for instance via a cone seal. These lines communicate with theinterior of the tubular high-pressure reservoir 1, that is, the throughbore 10, via connecting bores 11. The cross section of this recess ispreferably a circular area but it may also have some other shape, suchas oval. The special feature of the invention in this respect is thatthe connecting bores discharge into the through bore 10 eccentrically tothe longitudinal axis of the through bore, with an eccentricity e. Thedischarge is preferably effected tangentially. This affords theadvantage, mentioned at the outset, that the tension load on the wall ofthe high-pressure reservoir in the region of intersection of theconnecting bores with the longitudinal bore is reduced because in thisconstruction the individual loads are superimposed only vectorially onone another. The connections 2 are used to connect the high-pressurefuel reservoir to electrically controlled fuel injection valves.

The foregoing relates to preferred exemplary embodiments of theinvention, it being understood that other variants and embodimentsthereof are possible within the spirit and scope of The invention, thelatter being defined by the appended claims.

What is claimed is:
 1. A high-pressure fuel reservoir for a fuelinjection system for internal combustion engines, having a high-pressurefuel pump that supplies fuel to the high-pressure fuel reservoir, fromwhich the fuel is delivered to electrically controlled injection valvesfor injection into the combustion chambers of a self-igniting internalcombustion engine, the high-pressure fuel reservoir comprises anelongated strong metal tubular body that is provided with threedifferent high pressure connections (2, 6, 7) for fuel delivery and fueloutflow, the connections are embodied as connection stubs, from each ofsaid connections one connecting bore discharges into the tubular bodyeccentrically to a linear axis of the tubular body.
 2. A high-pressurefuel reservoir of claim 1, in which the connecting bores discharge at atangent to an inner wall of the tubular body.
 3. A high-pressure fuelreservoir of claim 2, in which the internal cross section of the tubularbody is a circular area.
 4. A high-pressure fuel reservoir of claim 1,in which the tubular body is shaped by forging, with separate connectionstubs (2, 6, 7) likewise formed on by forging.
 5. A high-pressure fuelreservoir of claim 2, in which, the tubular body is shaped by forging,with separate connection stubs (2, 6, 7) likewise formed on by forging.6. A high-pressure fuel reservoir of claim 3, in which, the tubular bodyis shaped by forging, with separate connection stubs (2, 6, 7) likewiseformed on by forging.
 7. A high-pressure fuel reservoir of claim 1, inwhich fastening tabs are formed onto the tubular body.
 8. Ahigh-pressure fuel reservoir of claim 2, in which fastening tabs areformed onto the tubular body.
 9. A high-pressure fuel reservoir of claim3, in which fastening tabs are formed onto the tubular body.
 10. Ahigh-pressure fuel reservoir of claim 4, in which fastening tabs areformed onto the tubular body.